Air lock

ABSTRACT

AIR LOCK FOR INTRODUCING MATERIAL INTO AN AIR CONVEYING LINE WHILE PREVENTING BLOWBACK TO A MATERIAL SUPPLY CONTAINER. MATERIAL MOVES INTO A RECEIVER AND IS CARRIED TO A MIXING CHAMBER FOR ENTRAINMENT BY AN AIRSTREAM. A SWINGING GATE, SEALED EXCEPT AT THE BOTTOM, CONTROLS FLOW OF MATERIAL INTO THE MIXING CHAMBER, AND THE ENTRAINING AIR ENTERS THE CHAMBER AND FLOWS ACROSS THE BACK OF THE GATE, URGING THE GATE TOWARD CLOSED POSITION. THE GATE IS MECHANICALLY URGED TOWARD CLOSED POSITION ALSO. THE GATE IS PROVIDED WITH SEALS TO COMPLETELY SHUT OFF SUPPLY OF MATERIAL, AND THE GATE AND ITS SEAT COOPERATE TO CUT THROUGH MATERIAL AT THE GATE TO INSURE COMPLETE CLOSURE. BLOWBACK TO THE MATERIAL SUPPLY IS KPREVENTED BY AN AIR OUTLET OUTSIDE THE MIXING CHAMBER ADJACENT THE GATE, AND BY A SURGE CHAMBER ADJACENT THE RECEIVER. CONVEYING AIR CAN BE BYPASSED TO CLEAN THE AIR LOCK.

United States Patent [72] Inventor Joseph S. Herr P.0. Box 1416, Wickenburg, Ariz. 85358 [21] ApplNo 849,108 [22) Filed Aug. 11, 1969 [45] Patented June 28, 1971 [54] AIR LOCK 8 Claims, 5 Drawing Figs.

[52] US. Cl 302/50 [51] Int. Cl B65g 53/40 ['50] Field of Search 302/50 [56] References Cited UNITED STATES PATENTS 2,299,470 10/1942 Davis 302/50 3,099,496 7/1963 Kayser 302/50 3,460,869 8/1969 Herr 302/50 Primary Examiner-Andres H. Nielsen AtlorneyMason, Fenwick and Lawrence ABSTRACT: Air lock for introducing material into an air conveying line while preventing blowback to a material supply container. Material moves into a receiver and is carried to a mixing chamber for entrainment by an airstream. A swinging gate, sealed except at the bottom, controls flow of material into the mixing chamber, and the entraining air enters the chamber and flows across the back of the gate, urging the gate toward closed position. The gate is mechanically urged toward closed position alsov The gate is provided with seals to completely shut off supply of material, and the gate and its seat cooperate to cut through material at the gate to insure complete closure. Blowback to the material supply is prevented by an air outlet outside the mixing chamber adjacent the gate, and by a surge chamber adjacent the receiver. Conveying air can be bypassed to clean the air lock.

AIR LOCK BACKGROUND OF THE INVENTION This invention relates to air locks for use in air conveying systems, and more particularly to air locks which have no continuously moving parts, but remain in open condition during operation, such as the type disclosed in my copending application Ser. No. 673,705, entitled Air Lock, filed Oct. 9, 1967, now Pat. No. 3,460,869, filed Aug. 12, 1969.

The air lock of my prior application solved many of the problems of systems which propose to admit material to be conveyed into a moving airstream. It provided a system which dispensed with parts which must move periodically, or continuously, during material feeding, and, at the same time, substantially eliminated blowback of air into the supply of materialto be fed.

Study of the prior construction has shown that it is efficient in general operation, but some features of the operation could be improved. For example, the entry of the conveying air beneath the swinging gate controlling admission of material to the mixing chamber at times causes turbulence in the mixing chamber. Due to the necessity of sealing the valve gate around the full circumference of the auger pipe outlet, material may get between the pipe and the gate preventing complete closure of the gate.

SUMMARY OF THE INVENTION The general object of the present invention is to provide an air lock which will be an improvement over the air lock disclosed in the above mentioned application.

A more specific object of the invention is to provide an air lock of the type of the prior application wherein the conveying air enters above the gate controlling material entrance to the mixing chamber, and flows along the back of the gate to urge the gate toward closed position and to meet, and tnix with, the incoming material without turbulence.

Another object is the provision of such structure in which the gate is continuously sealed along its sides, and only the bottom edge is sealed by closing, and in which the inflowing conveying air serves to aid in maintaining the seal.

A further object is to provide an air lock having no ledges, or other projections, about the bottom of the mixing chamber upon which material may lodge and prevent proper closing of the gate.

Still another object of the invention is to provide such an air lock in which the swinging gate and its seat have companion surfaces to cut through material lodged at the gate seat to insure complete closure of the gate.

Yet a further object is to provide adjustable gate-closing means, whereby closing pressure on the gate can be varied under changing circumstances.

It is also an object of the invention to provide the material auger tube with a controlled vent to further control blowback into the material supply.

A still further object is to provide an air lock of the type described wherein a valved bypass for the conveying air is used to permit conveying air to clean the system.

Other objects of the invention will become apparent from the following description of one practical embodiment thereof, when taken in conjunction with the drawings which accompany, and form part of, this specification.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a perspective view of an air lock embodying the principles of the present invention;

FIG. 2 is a longitudinal, vertical section through the structure, taken on the line 2-2 of FIG. 1;

FIG. 3 is a fragmentary portion of the structure shown in FIG. 2, but with the material-control gate open and the conveying airpath being shown;

FIG. 4 is a transverse, vertical section through the mixing chamber, taken on the line 4-4 of FIG. I; and

FIG. 5 is an exploded perspective view of the material-control gate and gate seat.

DESCRIPTION OF THE PREFERRED EMBODIMENT The air lock 1 of the present invention is adapted to be connected to the outlet 2 of a container, or hopper, 3. The air lock is designed to transfer material emerging from the hopper outlet to an air conveying line 4 without blowback of the conveyor air to the hopper.

The hopper 3 is shown as having downwardly converging sides 5 extending to the outlet 2. The bottom of the hopper outlet has a peripheral flange 6 which is connected by suitable bolts to the inlet end of the air lock 1.

The air lock consists essentially of a receiver 8, having a base section 9 and a header section 10, a feed tube 11 and a mixing chamber 12 which is included in the air-conveying line 4. Material (usually granular material) flows from the hopper 3 into the receiver 8 and is carried through the base section 9 and feed tube 11 to the mixing chamber 12 where it is entrained in the airstream flowing through the line 4.

The base section 9 of the receiver 8 is in the form of an elongated trough having its longitudinal sides 13 converging downwardly to a rounded bottom 14, and has end walls 15 and 16. A floating auger 17 is positioned in the bottom of the trough and extends through an opening 18 in the end wall 16 and along the feed tube 11, which is connected to the end wall 16 about the opening 18. The shaft 19 of the auger extends through the end wall 15 of the trough, and carries a drive pulley, or sprocket, 20 outside the end wall 15. The receiver is divided into two compartments by means of a baffle 21 which extends the full height and width of the receiver, except for an arcuate opening22 at the bottom to allow passage of the auger 17. The compartment between the baflle and the end wall 15 forms a material chamber 23, and the compartment between the baffle and the end wall 16 forms a surge chamber 24.

The feed tube 11 is simply a length of tubular material forming a housing about the extended portion of the auger l7, and of sufficient length to extend from the receiver base to the mixing chamber 12. The tube provides a confining passage for the material while moving from the base section to the material chamber.

The structure described thus far is substantially the same as that disclosed in the above mentioned prior application.

The mixing chamber 12 is in the form of a substantially rectangular housing having a backwall 25 connected to a flange 26 about the outlet end of the feed tube 11. The backwall contains an opening 27 in communication with the open end of the feed tube 11. Flow of material from the feed tube into the mixing chamber is controlled by means ofa gate 28. Normal flow of air through the air line 4 moves through a supply line 29 into a manifold 30 located on top of the mixing chamber 12, and then, through an opening 31 in the bottom of the manifold, into the mixing chamber. Opening 31 is located almost directly above the gate 28, so that air entering the chamber sweeps down across the back of the gate toward the bottom of the mixing chamber. The bottom 32 of the chamber declines from the gate wall 25 toward an opposite wall 33 of the chamber. The material conveying section 34 of the air line 4 connects to an outlet 35 at the bottom of the mixing chamber at the juncture of the wall 33 and the bottom 32. Thus, air entering at the top of the chamber adjacent the wall 25 sweeps downwardly across gate 28, and, picking up material as it flows into the chamber through the gate, flows across the bottom of the chamber and through the outlet 35 into the material-conveying section 34.

Gate 28 consists of a frame 36, for mounting on the wall 25 of the mixing chamber, and a swinging gate valve 37 pivotally carried by the frame 36. The frame is in the form of a rectangular mounting plate 38, which is attached flush against the vertical backwall 25 of the mixing chamber. The plate has a central opening 39 of desired shape and of sufficient size to wholly span the exit end ofthe feed tube 11. A valve seat 40 in the form of a flange projecting horizontally outward from the plate into the mixing chamber, surrounds at least the vertical sides and arcuate bottom of the opening. Side wings 41 are located along each side of the valve seat, and project beyond the valve seat into the mixing chamber a distance sufficiently great to span the normal swinging arc of movement of the gate valve 37. These wings will maintain contact with the side edges of the gate valve, as will be explained, to maintain a closure at the sides of the valve during all operative movement of the gate valve.

Mounting plate 38 also has spaced ears 42 at either side of, and just above, the top of the opening 39 to mount the gate valve. The gate valve consists of a pivot rod 43, a valve plate 44, a gasket 45 and a gasket-holding frame 46. Pivot rod 43 has projecting ends which fit into openings in the mounting ears 42 to pivotally hang the gate valve on the frame. Valve plate 44 is welded, or otherwise secured, to the pivot rod, and has a size and shape which approximates that of the inner side of the valve seat 40 to permit the valve plate to move freely into the opening defined by the valve seat. The gasket 45 is substantially U-shaped, having the bottom portion of the U in the form of an arcuate segment 47, from the top of which upstanding legs 48 extend to the top of the valve plate 44. The legs 48 are spaced horizontally so that they lie along the side edges of the valve plate, projecting sufficiently beyond the plate edges to seat upon the sides of the valve seat 40 and have sealing contact with the projecting wings 41. The bottom arcuate segment of the gasket lies against the lower portion of the valve plate and projects beyond its lower edge for sealing engagement with the lower arcuate portion of the valve seat. The segmental portion of the gasket may project at either side beyond the legs 48, as at 49, to provide sealing edges for contact with the lower arcuate edges of the side wings 41. The gasket holding frame 46 is of substantially the same shape as the gasket, but its outer dimensions are such that its outer edges overlie the perimeter of the gate plate, leaving the projecting portions of the gaskets at the sides and bottom free to flex for proper sealing contact with the respective members of the frame against which they seat.

One of the ends of the pivot rod 43 extends beyond its mounting ear 42 and through the adjacent sidewall of the mixing chamber 12. The projecting end carries a gate-biasing arm 50. A biasing spring 51 is connected between the outer end of the arm 50 and the lower side of the mixing chamber 12. A turnbuckle, or other spring tensioning device, 52 may be used in the connection between the mixing chamber and the spring so that the tension of the spring can be changed as desired to vary the bias upon the gate 28. With this arrangement, the gate valve is always urged toward its seat to cut off flow of material into the mixing chamber. This, together with the flow of air into the chamber across the back of the gate valve, would insure closing of the gate at all times when there is insufficient pressure of material against the back of the valve to force it open against the biasing and air pressures. Under these conditions, the feed tube has to be full, or substantially full, in order for the gate valve to open, so that the material being fed forms an added block to prevent blowback of air through the feed tube.

Near the outlet end of the auger case, or feed tube, there is an outlet 53, in the form of a vertical pipe in open communication with the feed tube. The top of the pipe is controlled by a manual valve 54, so that air which might enter through the gate 28 may have a free exit to atmosphere. This will cut down on the amount of air which might get back to the surge chamber, and further eliminate the possibility of blowback into the feed hopper.

In order to provide means for cleaning the system, a slide valve 55 is arranged at the top of the receiving chamber 8 to cut off communication with the feed hopper. The valve is shown as a gate member 56, which is slidable in grooves 57 in the walls of the receiving chamber. The gate is shown as movable into a housing 58, outside the receiving chamber, so as to reduce the possibility of air leakage into the receiver. An air line 59 is connected from the manifold 30 to the upper part of the receiver 8 below the position of the valve 55. This line is provided with a cutoff valve 60 to permit the line to be closed offduring normal operation of the air lock.

When it is desired to clean the system, the valve 55 will be closed to shut off flow of material from the hopper into the receiver, the valve 54 on the outlet pipe 53 will be closed, and valve 60 in the air line 59 will be opened. This will permit air to flow from the manifold 30 through the air line 59 into the receiver, and from the receiver'through the various parts of the air lock and out through the control valve 28 to join air moving in the normal direction from the manifold 30 through the opening 31 into the mixing chamber 12. The air will flow out of the mixing chamber through the conveying line 34. When the lock is clean, valve 59 will be closed and valves 54 and 55 will be opened to return the system to proper condition for normal operation.

In operating the system material will flow from the feed hopper 3 into the receiver 8, where it is picked up by the auger 17 and carried to the gate 28 controlling entrance of material into the mixing chamber. Air will be flowing through the air line 4, entering the mixing chamber through opening 38, and flowing downwardly through the mixing chamber across the back of the closed gate 37 and across the bottom of the chamber and out through the exit 35. As material is fed along the feed tube ll 1, it will exert a pressure against the back of the gate 37, and when the pressure is sufiicient to overcome the air flow across the back of the gate and the tension of spring 51, it will force the gate open allowing material to enter the feed chamber and be mixed with the air flowing through the chamber to be carried out to the conveying line for delivery at a predetermined point.

Whenever the material flow is reduced, the combined action of the spring 51 and the flow of air across the back of the gate will cause the gate to close. The particular mounting of the gate, with the side wings 41 provides an opening for material at the bottom of the gate so that the flow into the gate chamber is downwardly. Whenever the pressure decreases and the gate closes, the action of the gate plate against the relatively sharp upstanding edges of the valve seat 40, will cut through any material that might be lodged against the edge of the opening. The gasket on the gate will be in sealing contact with the wings 41 as the gate moves towards closed position, and these portions of the gasket, together with the lower portion 47 will provide a complete seal for the gate when the gate is in closed position. Here, again, the particular arrangement of the air flow with respect to the valve will be effective to maintain the seal. The downward flow of air against the back of the valve will exert an inward pressure on the gasket members to hold them in good sealing contact with the valve seat. Whenever it is desired to clean the system, the valves 54 and 55 can be closed, and valve 68 opened to allow the air to move through the bypass line 59 into the receiver, as described above. This permits the use of the conveying air as a cleaning medium.

While one specific embodiment of the invention has been described and illustrated in detail, the construction disclosed is merely for purposes of illustration, and changes may be made and still obtain the same result.

I claim:

I. In an air lock having a material-receiving chamber, a mixing chamber, an auger feed assembly to feed material from the receiving chamber to the mixing chamber, a surge chamber adjacent the receiving chamber in communication with the auger feed assembly, an air-conveying line extending to, through and from the mixing chamber, a valve in the mixing chamber controlling flow of material from the auger feed assembly to the mixing chamber, the improvement comprising, the mixing chamber having a valve seat about an opening in one vertical wall in communication with the auger feed assembly, the valve being pivotally mounted about the valve seat for swinging movement away from and toward the valve seat, and the air-conveying line having an inlet to the mixing chamber above the valve and an outlet from the mixing chamber adjacent the bottom of the wall opposite the wall having the valve seat, whereby conveying air will flow through the mixing chamber across the valve urging the valve toward the valve seat.

2. In an air lock as claimed in claim 1 wherein, there are means connected to the valve to yieldingly bias the valve toward the valve seat;

3. in an air lock as claimed in claim 2 wherein, there are means to adjust the valve-biasing means to vary the degree of bias imposed upon the valve.

4. In an air lock as claimed in claim 1 wherein, there are vertical wings at the sides of the valve seat and the valve is in sealing contact with the wings throughout its normal arc of opening swing to cause material entering the mixing chamber from the auger feed assembly to flow downwardly beneath the bottom of the valve for smooth entry into the conveying air.

5. in an air lock as claimed in claim 4 wherein, the valve has a gasket projecting beyond its sides and bottom for sealing contact with the wings and the valve seat.

6. In an air lock as claimed in claim 5 wherein, the valve and the valve seat have companion surfaces to cut through material about the valve seat as the valve closes.

7. In an air lock as claimed in claim 1 wherein, there is an air outlet open to atmosphere on the auger feed assembly adjacent the mixing chamber, and a valve on the air outlet to open and close the outlet.

8. In an air lock as claimed in claim 7 wherein, there is a closure valve for the receiving chamber remote from the auger feed assembly, an air bypass line from the air-conveying line anterior to the mixing chamber to the receiving chamber below the closure valve, and a shutoff valve in the bypass line. 

